BALTIMORE (AP) - Four men have been indicted in the death of a man who was operating an unauthorized taxicab in Baltimore, witnessed a passenger's arrest and later was found shot to death.

Prosecutors revealed details Thursday of the 2011 killing of Robert Givens. Police say the case is part of Baltimore's continuing problem of witness intimidation.

In this case, The Baltimore Sun reports 55-year-old Givens turned down a bribe to give false testimony in a drug and guns case of his taxi passenger. When he turned down the bribe, he was targeted for murder. He was shot to death in front of his Baltimore County home.